Device for preventing clogging in centrifugal pumps



July 7, 1953 L. J. DAWSON 2,644,403

DEVICE FOR PREVENTING CLOGGING IN CENTRIFUGAL PUMPS Filed March 5, 1952 INVENTOR L535 J. DAWSON HIS AT-TOR'NEY.

Patented July 7, 1953 TENT OFFICE DEVICE FOR PREVENTING CLOGGING IN CENTRIFUGAL rUMrs Lewis J. Dawson, Phillipsburg, N. J., assignor to Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application March 5, 1952, Serial No. 274,976

(Cl. lose-10a) 1 Claim.

This invention relates to centrifugal pumps, and more particularly to a device for preventing clogging in centrifugal pumps of the type having wearing rings to limit the leakage of fluid along the impeller from the discharge chamber to the suction chamber.

It is customary, in centrifugal pumps, to pro= vide the exterior of the skirt portion which defines the eye of the impeller and the immediately encircling part of the pump casing, and which separates the suction and discharge chambers for the impeller, with rings that serve to control the amount of leakage of fluid from the discharge chamber to the suction chamber.

The principal reason for providing the clearance which permits of such leakage is that it has been found to be inadvisable to have a close fit between the rings because of certain unfavorable conditions incident to the operation of the pump, as for example the vibratory movement of the rotative parts which often occurs during the accelerating period. Obviously, the liquid thus passing between the rings will carry with it entrained solids which, if of a fibrous nature, will accumulate and be compacted in the clear= ance space and seriously damage the rings.

It is accordingly an object of the invention to prevent the clogging of the clearance space between the impeller and easing rings by material entrained in the fluid being pumped.

A more specific object is to effect the speedy comminution of materials tending to accumulate in such space.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings accompanying this specification and in which similar reference numerals refer to similar parts,

Figure 1 is a longitudinal elevation, partly broken away, of so much of a centrifugal pump as will serve to illustrate a practical application of the invention,

Figure 2 is a transverse view taken through Figure 1 on the line 2--2, and

Figures 3 and 4 are perspective views of a casing ring and an impeller ring, respectively.

Referring more particularly to the drawings, 2|! designates so much of a centrifugal pump as will serve to illustrate a practical application of the invention, 2| is a pump casing and 22 a shaft charge chamber 24 which has the usual outlet opening 26. The impeller 25 and the wall 21 of the casing 2! separating the suction chamber from the discharge chamber are provided with rings 23 and 29, respectively, which cooperate to limit the amount of leakage of fluid from the discharge chamber 24 along the impeller back to the suction chamber 23.

The ring 28 is suitably attached to and encircles the skirt portion 38 defining the eye 3| of the impeller and lies within the ring 29 which is shown interlockingly connected to the casing by an annular tongue and groove connection 32. The bore of the ring 29 is slightly larger than the outer diameter of the ring 28 to define a clearance space 33 between the rings. The space 33 is of no greater width than necessary to prevent the impeller ring from striking the casing ring under all conditions of operation in order that the loss of discharge fluid may be held to a minimum.

In accordance with the practice of the invention, the rings 28 and 29 are provided with means for breaking up and comminuting accumulations of fibres or other solids that may enter and tend to clog the clearance space 33. To this end the casing ring 29 is provided in its inner surface 34 with a series of slots 35 which may, as illustrated, be equally spaced with respect to each other. The slots 35 extend axially of the ring 29 from one side of the ring to the other. They may be of any suitable depth and the lines of juncture of the opposed side surfaces 36 of the slots with the inner surface 34 of the ring constitute cutting edges 31.

Similarly, a series of equally spaced grooves 38 is formed in the outer surface 39 of the impeller ring 28 to define cutting edges 40 at the junctures of their opposed side surfaces 4| with the surface 39. The grooves 38 also extend entirely across the surface 39 but are formed diagonally therein so that, in cooperation with the cutting edges 31, they will exert a shearing action on material entering the space 33 and reduce it to a condition in which the fluid flowing through the space 33 may readily wash it back into the suction chamber.

Iclaim:

In a centrifugal pump, a. casing having a suction chamber and a discharge chamber, an impeller in the casing for pumping liquid from the suction chamber to the discharge chamber, a ring on and encircling the inlet end of the impeller, a ring in the casing encircling the firstmentioned ring and having its internal surface spaced from the ring on the impeller to define a clearance therebetween for controlling the degree of leakage from the discharge chamber to the suction chamber, grooves in the inner surface of the casing ring extending axially of the casing ring, cutting edges at the junctures of the grooves and the inner surface of the casing ring, slots in the peripheral surface of the impeller ring arranged diagonally of the impeller ring, and cutting edges at the junctures of the slots and the peripheral surface of the impeller ring to cooperate with the first-mentioned cutting edges for comminuting solids in the clearance between the rings.

LEWIS J. DAWSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 10 2,050,104 Lauchenauer Aug. 4, 1936 2,190,670 Mann Feb, 20, 1940 

